The Tōhoku earthquake and tsunami may have struck three years ago, but radioactive water from Japan's beleaguered Fukushima nuclear power plant is now being detected near Canada's West Coast. Scientists will be monitoring North American shores for the next two months, but projections point to good news.
Minute traces of radionuclides were recently detected off the coast of British Columbia. The contaminated water has yet to reach Washington, California, or Hawaii. According to researchers who met yesterday at the annual American Geophysical Union's Ocean Sciences Meeting in Honolulu, radiation levels will increase as contaminants slowly swell eastwards.
As noted by researchers at Woods Hole Oceanographic Institution (WHOI), radioactive contaminants from Fukushima are being pushed across the Pacific Ocean by currents, the strongest of which is the Kuroshio, and spread along the West Coast of North America by complex coastal processes. Their models correctly predicted that radionuclides from Fukushima would begin to arrive on the West Coast in early 2014. At first, these contaminated waters will appear in the north (Alaska and British Columbia) and then move further south in coming years before appearing in Hawaii in small amounts.
WHOI is currently monitoring water in 16 locations:
During the nuclear accident, the Fukushima plant released several radioactive isotopes, including iodine-131, cesium-134, and cesium-137. Cesium-137 has a half-life of 30 years, so it'll stay in the environment for a few more decades (relatedly, some of the Cesium-137 was produced by A-bomb tests during the 1950s and 1960s — but the radionuclides from Fukushima are expected to be very evident). Cesium-134, which has a half-life of just two years, has yet to be detected on North American beaches.
But the concentrations of these contaminants are expected to be well below limits set by the U.S. Environmental Protection Agency (EPA); this is not an environmental or human-health threat. For drinking water, cesium-137 levels can't be above 7,400 Becquerels per cubic meter (Bq/m3), or 10,000 Bq/m3 in Canada. For comparison, waters in the Baltic Sea following the Chernobyl disaster reached 1,000 Bq/m3.
The level of contaminants in the waters that just reached North America are less than 1 Bq/m3 of water. Researchers predict that, at worst, levels for Cesium-137 won't exceed 27 Bq/m3 (which is predicted to happen by mid-2015), and levels for cesium-134 won't exceed 2 Bq/m3.